4 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
6 * This file is released under the GPL.
9 #include <linux/blkdev.h>
10 #include <linux/ctype.h>
11 #include <linux/device-mapper.h>
13 #include <linux/init.h>
14 #include <linux/kdev_t.h>
15 #include <linux/list.h>
16 #include <linux/mempool.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/vmalloc.h>
22 #include "dm-bio-list.h"
25 #define DM_MSG_PREFIX "snapshots"
28 * The percentage increment we will wake up users at
30 #define WAKE_UP_PERCENT 5
33 * kcopyd priority of snapshot operations
35 #define SNAPSHOT_COPY_PRIORITY 2
38 * Each snapshot reserves this many pages for io
40 #define SNAPSHOT_PAGES 256
42 struct workqueue_struct *ksnapd;
43 static void flush_queued_bios(void *data);
45 struct pending_exception {
49 * Origin buffers waiting for this to complete are held
52 struct bio_list origin_bios;
53 struct bio_list snapshot_bios;
56 * Short-term queue of pending exceptions prior to submission.
58 struct list_head list;
61 * The primary pending_exception is the one that holds
62 * the ref_count and the list of origin_bios for a
63 * group of pending_exceptions. It is always last to get freed.
64 * These fields get set up when writing to the origin.
66 struct pending_exception *primary_pe;
69 * Number of pending_exceptions processing this chunk.
70 * When this drops to zero we must complete the origin bios.
71 * If incrementing or decrementing this, hold pe->snap->lock for
72 * the sibling concerned and not pe->primary_pe->snap->lock unless
77 /* Pointer back to snapshot context */
78 struct dm_snapshot *snap;
81 * 1 indicates the exception has already been sent to
88 * Hash table mapping origin volumes to lists of snapshots and
89 * a lock to protect it
91 static kmem_cache_t *exception_cache;
92 static kmem_cache_t *pending_cache;
93 static mempool_t *pending_pool;
96 * One of these per registered origin, held in the snapshot_origins hash
99 /* The origin device */
100 struct block_device *bdev;
102 struct list_head hash_list;
104 /* List of snapshots for this origin */
105 struct list_head snapshots;
109 * Size of the hash table for origin volumes. If we make this
110 * the size of the minors list then it should be nearly perfect
112 #define ORIGIN_HASH_SIZE 256
113 #define ORIGIN_MASK 0xFF
114 static struct list_head *_origins;
115 static struct rw_semaphore _origins_lock;
117 static int init_origin_hash(void)
121 _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head),
124 DMERR("unable to allocate memory");
128 for (i = 0; i < ORIGIN_HASH_SIZE; i++)
129 INIT_LIST_HEAD(_origins + i);
130 init_rwsem(&_origins_lock);
135 static void exit_origin_hash(void)
140 static inline unsigned int origin_hash(struct block_device *bdev)
142 return bdev->bd_dev & ORIGIN_MASK;
145 static struct origin *__lookup_origin(struct block_device *origin)
147 struct list_head *ol;
150 ol = &_origins[origin_hash(origin)];
151 list_for_each_entry (o, ol, hash_list)
152 if (bdev_equal(o->bdev, origin))
158 static void __insert_origin(struct origin *o)
160 struct list_head *sl = &_origins[origin_hash(o->bdev)];
161 list_add_tail(&o->hash_list, sl);
165 * Make a note of the snapshot and its origin so we can look it
166 * up when the origin has a write on it.
168 static int register_snapshot(struct dm_snapshot *snap)
171 struct block_device *bdev = snap->origin->bdev;
173 down_write(&_origins_lock);
174 o = __lookup_origin(bdev);
178 o = kmalloc(sizeof(*o), GFP_KERNEL);
180 up_write(&_origins_lock);
184 /* Initialise the struct */
185 INIT_LIST_HEAD(&o->snapshots);
191 list_add_tail(&snap->list, &o->snapshots);
193 up_write(&_origins_lock);
197 static void unregister_snapshot(struct dm_snapshot *s)
201 down_write(&_origins_lock);
202 o = __lookup_origin(s->origin->bdev);
205 if (list_empty(&o->snapshots)) {
206 list_del(&o->hash_list);
210 up_write(&_origins_lock);
214 * Implementation of the exception hash tables.
216 static int init_exception_table(struct exception_table *et, uint32_t size)
220 et->hash_mask = size - 1;
221 et->table = dm_vcalloc(size, sizeof(struct list_head));
225 for (i = 0; i < size; i++)
226 INIT_LIST_HEAD(et->table + i);
231 static void exit_exception_table(struct exception_table *et, kmem_cache_t *mem)
233 struct list_head *slot;
234 struct exception *ex, *next;
237 size = et->hash_mask + 1;
238 for (i = 0; i < size; i++) {
239 slot = et->table + i;
241 list_for_each_entry_safe (ex, next, slot, hash_list)
242 kmem_cache_free(mem, ex);
248 static inline uint32_t exception_hash(struct exception_table *et, chunk_t chunk)
250 return chunk & et->hash_mask;
253 static void insert_exception(struct exception_table *eh, struct exception *e)
255 struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)];
256 list_add(&e->hash_list, l);
259 static inline void remove_exception(struct exception *e)
261 list_del(&e->hash_list);
265 * Return the exception data for a sector, or NULL if not
268 static struct exception *lookup_exception(struct exception_table *et,
271 struct list_head *slot;
274 slot = &et->table[exception_hash(et, chunk)];
275 list_for_each_entry (e, slot, hash_list)
276 if (e->old_chunk == chunk)
282 static inline struct exception *alloc_exception(void)
286 e = kmem_cache_alloc(exception_cache, GFP_NOIO);
288 e = kmem_cache_alloc(exception_cache, GFP_ATOMIC);
293 static inline void free_exception(struct exception *e)
295 kmem_cache_free(exception_cache, e);
298 static inline struct pending_exception *alloc_pending_exception(void)
300 return mempool_alloc(pending_pool, GFP_NOIO);
303 static inline void free_pending_exception(struct pending_exception *pe)
305 mempool_free(pe, pending_pool);
308 int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new)
312 e = alloc_exception();
318 insert_exception(&s->complete, e);
325 static int calc_max_buckets(void)
327 /* use a fixed size of 2MB */
328 unsigned long mem = 2 * 1024 * 1024;
329 mem /= sizeof(struct list_head);
335 * Rounds a number down to a power of 2.
337 static inline uint32_t round_down(uint32_t n)
345 * Allocate room for a suitable hash table.
347 static int init_hash_tables(struct dm_snapshot *s)
349 sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets;
352 * Calculate based on the size of the original volume or
355 cow_dev_size = get_dev_size(s->cow->bdev);
356 origin_dev_size = get_dev_size(s->origin->bdev);
357 max_buckets = calc_max_buckets();
359 hash_size = min(origin_dev_size, cow_dev_size) >> s->chunk_shift;
360 hash_size = min(hash_size, max_buckets);
362 /* Round it down to a power of 2 */
363 hash_size = round_down(hash_size);
364 if (init_exception_table(&s->complete, hash_size))
368 * Allocate hash table for in-flight exceptions
369 * Make this smaller than the real hash table
375 if (init_exception_table(&s->pending, hash_size)) {
376 exit_exception_table(&s->complete, exception_cache);
384 * Round a number up to the nearest 'size' boundary. size must
387 static inline ulong round_up(ulong n, ulong size)
390 return (n + size) & ~size;
393 static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
396 unsigned long chunk_size;
399 chunk_size = simple_strtoul(chunk_size_arg, &value, 10);
400 if (*chunk_size_arg == '\0' || *value != '\0') {
401 *error = "Invalid chunk size";
406 s->chunk_size = s->chunk_mask = s->chunk_shift = 0;
411 * Chunk size must be multiple of page size. Silently
412 * round up if it's not.
414 chunk_size = round_up(chunk_size, PAGE_SIZE >> 9);
416 /* Check chunk_size is a power of 2 */
417 if (chunk_size & (chunk_size - 1)) {
418 *error = "Chunk size is not a power of 2";
422 /* Validate the chunk size against the device block size */
423 if (chunk_size % (bdev_hardsect_size(s->cow->bdev) >> 9)) {
424 *error = "Chunk size is not a multiple of device blocksize";
428 s->chunk_size = chunk_size;
429 s->chunk_mask = chunk_size - 1;
430 s->chunk_shift = ffs(chunk_size) - 1;
436 * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size>
438 static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
440 struct dm_snapshot *s;
447 ti->error = "requires exactly 4 arguments";
452 origin_path = argv[0];
454 persistent = toupper(*argv[2]);
456 if (persistent != 'P' && persistent != 'N') {
457 ti->error = "Persistent flag is not P or N";
462 s = kmalloc(sizeof(*s), GFP_KERNEL);
464 ti->error = "Cannot allocate snapshot context private "
470 r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
472 ti->error = "Cannot get origin device";
476 r = dm_get_device(ti, cow_path, 0, 0,
477 FMODE_READ | FMODE_WRITE, &s->cow);
479 dm_put_device(ti, s->origin);
480 ti->error = "Cannot get COW device";
484 r = set_chunk_size(s, argv[3], &ti->error);
488 s->type = persistent;
493 init_rwsem(&s->lock);
494 spin_lock_init(&s->pe_lock);
495 s->table = ti->table;
497 /* Allocate hash table for COW data */
498 if (init_hash_tables(s)) {
499 ti->error = "Unable to allocate hash table space";
506 if (persistent == 'P')
507 r = dm_create_persistent(&s->store);
509 r = dm_create_transient(&s->store);
512 ti->error = "Couldn't create exception store";
517 r = kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client);
519 ti->error = "Could not create kcopyd client";
523 /* Metadata must only be loaded into one table at once */
524 r = s->store.read_metadata(&s->store);
526 ti->error = "Failed to read snapshot metadata";
530 bio_list_init(&s->queued_bios);
531 INIT_WORK(&s->queued_bios_work, flush_queued_bios, s);
533 /* Add snapshot to the list of snapshots for this origin */
534 /* Exceptions aren't triggered till snapshot_resume() is called */
535 if (register_snapshot(s)) {
537 ti->error = "Cannot register snapshot origin";
542 ti->split_io = s->chunk_size;
547 kcopyd_client_destroy(s->kcopyd_client);
550 s->store.destroy(&s->store);
553 exit_exception_table(&s->pending, pending_cache);
554 exit_exception_table(&s->complete, exception_cache);
557 dm_put_device(ti, s->cow);
558 dm_put_device(ti, s->origin);
567 static void snapshot_dtr(struct dm_target *ti)
569 struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
571 flush_workqueue(ksnapd);
573 /* Prevent further origin writes from using this snapshot. */
574 /* After this returns there can be no new kcopyd jobs. */
575 unregister_snapshot(s);
577 kcopyd_client_destroy(s->kcopyd_client);
579 exit_exception_table(&s->pending, pending_cache);
580 exit_exception_table(&s->complete, exception_cache);
582 /* Deallocate memory used */
583 s->store.destroy(&s->store);
585 dm_put_device(ti, s->origin);
586 dm_put_device(ti, s->cow);
592 * Flush a list of buffers.
594 static void flush_bios(struct bio *bio)
601 generic_make_request(bio);
606 static void flush_queued_bios(void *data)
608 struct dm_snapshot *s = (struct dm_snapshot *) data;
609 struct bio *queued_bios;
612 spin_lock_irqsave(&s->pe_lock, flags);
613 queued_bios = bio_list_get(&s->queued_bios);
614 spin_unlock_irqrestore(&s->pe_lock, flags);
616 flush_bios(queued_bios);
620 * Error a list of buffers.
622 static void error_bios(struct bio *bio)
629 bio_io_error(bio, bio->bi_size);
634 static void __invalidate_snapshot(struct dm_snapshot *s,
635 struct pending_exception *pe, int err)
641 DMERR("Invalidating snapshot: Error reading/writing.");
642 else if (err == -ENOMEM)
643 DMERR("Invalidating snapshot: Unable to allocate exception.");
646 remove_exception(&pe->e);
648 if (s->store.drop_snapshot)
649 s->store.drop_snapshot(&s->store);
653 dm_table_event(s->table);
656 static void get_pending_exception(struct pending_exception *pe)
658 atomic_inc(&pe->ref_count);
661 static struct bio *put_pending_exception(struct pending_exception *pe)
663 struct pending_exception *primary_pe;
664 struct bio *origin_bios = NULL;
666 primary_pe = pe->primary_pe;
669 * If this pe is involved in a write to the origin and
670 * it is the last sibling to complete then release
671 * the bios for the original write to the origin.
674 atomic_dec_and_test(&primary_pe->ref_count))
675 origin_bios = bio_list_get(&primary_pe->origin_bios);
678 * Free the pe if it's not linked to an origin write or if
679 * it's not itself a primary pe.
681 if (!primary_pe || primary_pe != pe)
682 free_pending_exception(pe);
685 * Free the primary pe if nothing references it.
687 if (primary_pe && !atomic_read(&primary_pe->ref_count))
688 free_pending_exception(primary_pe);
693 static void pending_complete(struct pending_exception *pe, int success)
696 struct dm_snapshot *s = pe->snap;
697 struct bio *origin_bios = NULL;
698 struct bio *snapshot_bios = NULL;
702 /* Read/write error - snapshot is unusable */
703 down_write(&s->lock);
704 __invalidate_snapshot(s, pe, -EIO);
709 e = alloc_exception();
711 down_write(&s->lock);
712 __invalidate_snapshot(s, pe, -ENOMEM);
718 down_write(&s->lock);
726 * Add a proper exception, and remove the
727 * in-flight exception from the list.
729 insert_exception(&s->complete, e);
730 remove_exception(&pe->e);
733 snapshot_bios = bio_list_get(&pe->snapshot_bios);
734 origin_bios = put_pending_exception(pe);
738 /* Submit any pending write bios */
740 error_bios(snapshot_bios);
742 flush_bios(snapshot_bios);
744 flush_bios(origin_bios);
747 static void commit_callback(void *context, int success)
749 struct pending_exception *pe = (struct pending_exception *) context;
750 pending_complete(pe, success);
754 * Called when the copy I/O has finished. kcopyd actually runs
755 * this code so don't block.
757 static void copy_callback(int read_err, unsigned int write_err, void *context)
759 struct pending_exception *pe = (struct pending_exception *) context;
760 struct dm_snapshot *s = pe->snap;
762 if (read_err || write_err)
763 pending_complete(pe, 0);
766 /* Update the metadata if we are persistent */
767 s->store.commit_exception(&s->store, &pe->e, commit_callback,
772 * Dispatches the copy operation to kcopyd.
774 static void start_copy(struct pending_exception *pe)
776 struct dm_snapshot *s = pe->snap;
777 struct io_region src, dest;
778 struct block_device *bdev = s->origin->bdev;
781 dev_size = get_dev_size(bdev);
784 src.sector = chunk_to_sector(s, pe->e.old_chunk);
785 src.count = min(s->chunk_size, dev_size - src.sector);
787 dest.bdev = s->cow->bdev;
788 dest.sector = chunk_to_sector(s, pe->e.new_chunk);
789 dest.count = src.count;
791 /* Hand over to kcopyd */
792 kcopyd_copy(s->kcopyd_client,
793 &src, 1, &dest, 0, copy_callback, pe);
797 * Looks to see if this snapshot already has a pending exception
798 * for this chunk, otherwise it allocates a new one and inserts
799 * it into the pending table.
801 * NOTE: a write lock must be held on snap->lock before calling
804 static struct pending_exception *
805 __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
808 struct pending_exception *pe;
809 chunk_t chunk = sector_to_chunk(s, bio->bi_sector);
812 * Is there a pending exception for this already ?
814 e = lookup_exception(&s->pending, chunk);
816 /* cast the exception to a pending exception */
817 pe = container_of(e, struct pending_exception, e);
822 * Create a new pending exception, we don't want
823 * to hold the lock while we do this.
826 pe = alloc_pending_exception();
827 down_write(&s->lock);
830 free_pending_exception(pe);
834 e = lookup_exception(&s->pending, chunk);
836 free_pending_exception(pe);
837 pe = container_of(e, struct pending_exception, e);
841 pe->e.old_chunk = chunk;
842 bio_list_init(&pe->origin_bios);
843 bio_list_init(&pe->snapshot_bios);
844 pe->primary_pe = NULL;
845 atomic_set(&pe->ref_count, 0);
849 if (s->store.prepare_exception(&s->store, &pe->e)) {
850 free_pending_exception(pe);
854 get_pending_exception(pe);
855 insert_exception(&s->pending, &pe->e);
861 static inline void remap_exception(struct dm_snapshot *s, struct exception *e,
864 bio->bi_bdev = s->cow->bdev;
865 bio->bi_sector = chunk_to_sector(s, e->new_chunk) +
866 (bio->bi_sector & s->chunk_mask);
869 static int snapshot_map(struct dm_target *ti, struct bio *bio,
870 union map_info *map_context)
873 struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
876 struct pending_exception *pe = NULL;
878 chunk = sector_to_chunk(s, bio->bi_sector);
880 /* Full snapshots are not usable */
881 /* To get here the table must be live so s->active is always set. */
885 if (unlikely(bio_barrier(bio)))
888 /* FIXME: should only take write lock if we need
889 * to copy an exception */
890 down_write(&s->lock);
897 /* If the block is already remapped - use that, else remap it */
898 e = lookup_exception(&s->complete, chunk);
900 remap_exception(s, e, bio);
905 * Write to snapshot - higher level takes care of RW/RO
906 * flags so we should only get this if we are
909 if (bio_rw(bio) == WRITE) {
910 pe = __find_pending_exception(s, bio);
912 __invalidate_snapshot(s, pe, -ENOMEM);
917 remap_exception(s, &pe->e, bio);
918 bio_list_add(&pe->snapshot_bios, bio);
923 /* this is protected by snap->lock */
931 * FIXME: this read path scares me because we
932 * always use the origin when we have a pending
933 * exception. However I can't think of a
934 * situation where this is wrong - ejt.
936 bio->bi_bdev = s->origin->bdev;
944 static void snapshot_resume(struct dm_target *ti)
946 struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
948 down_write(&s->lock);
953 static int snapshot_status(struct dm_target *ti, status_type_t type,
954 char *result, unsigned int maxlen)
956 struct dm_snapshot *snap = (struct dm_snapshot *) ti->private;
959 case STATUSTYPE_INFO:
961 snprintf(result, maxlen, "Invalid");
963 if (snap->store.fraction_full) {
964 sector_t numerator, denominator;
965 snap->store.fraction_full(&snap->store,
968 snprintf(result, maxlen, "%llu/%llu",
969 (unsigned long long)numerator,
970 (unsigned long long)denominator);
973 snprintf(result, maxlen, "Unknown");
977 case STATUSTYPE_TABLE:
979 * kdevname returns a static pointer so we need
980 * to make private copies if the output is to
983 snprintf(result, maxlen, "%s %s %c %llu",
984 snap->origin->name, snap->cow->name,
986 (unsigned long long)snap->chunk_size);
993 /*-----------------------------------------------------------------
995 *---------------------------------------------------------------*/
996 static int __origin_write(struct list_head *snapshots, struct bio *bio)
998 int r = 1, first = 0;
999 struct dm_snapshot *snap;
1000 struct exception *e;
1001 struct pending_exception *pe, *next_pe, *primary_pe = NULL;
1003 LIST_HEAD(pe_queue);
1005 /* Do all the snapshots on this origin */
1006 list_for_each_entry (snap, snapshots, list) {
1008 down_write(&snap->lock);
1010 /* Only deal with valid and active snapshots */
1011 if (!snap->valid || !snap->active)
1014 /* Nothing to do if writing beyond end of snapshot */
1015 if (bio->bi_sector >= dm_table_get_size(snap->table))
1019 * Remember, different snapshots can have
1020 * different chunk sizes.
1022 chunk = sector_to_chunk(snap, bio->bi_sector);
1025 * Check exception table to see if block
1026 * is already remapped in this snapshot
1027 * and trigger an exception if not.
1029 * ref_count is initialised to 1 so pending_complete()
1030 * won't destroy the primary_pe while we're inside this loop.
1032 e = lookup_exception(&snap->complete, chunk);
1036 pe = __find_pending_exception(snap, bio);
1038 __invalidate_snapshot(snap, pe, -ENOMEM);
1044 * Either every pe here has same
1045 * primary_pe or none has one yet.
1048 primary_pe = pe->primary_pe;
1054 bio_list_add(&primary_pe->origin_bios, bio);
1059 if (!pe->primary_pe) {
1060 pe->primary_pe = primary_pe;
1061 get_pending_exception(primary_pe);
1066 list_add_tail(&pe->list, &pe_queue);
1070 up_write(&snap->lock);
1077 * If this is the first time we're processing this chunk and
1078 * ref_count is now 1 it means all the pending exceptions
1079 * got completed while we were in the loop above, so it falls to
1080 * us here to remove the primary_pe and submit any origin_bios.
1083 if (first && atomic_dec_and_test(&primary_pe->ref_count)) {
1084 flush_bios(bio_list_get(&primary_pe->origin_bios));
1085 free_pending_exception(primary_pe);
1086 /* If we got here, pe_queue is necessarily empty. */
1091 * Now that we have a complete pe list we can start the copying.
1093 list_for_each_entry_safe(pe, next_pe, &pe_queue, list)
1100 * Called on a write from the origin driver.
1102 static int do_origin(struct dm_dev *origin, struct bio *bio)
1107 down_read(&_origins_lock);
1108 o = __lookup_origin(origin->bdev);
1110 r = __origin_write(&o->snapshots, bio);
1111 up_read(&_origins_lock);
1117 * Origin: maps a linear range of a device, with hooks for snapshotting.
1121 * Construct an origin mapping: <dev_path>
1122 * The context for an origin is merely a 'struct dm_dev *'
1123 * pointing to the real device.
1125 static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1131 ti->error = "origin: incorrect number of arguments";
1135 r = dm_get_device(ti, argv[0], 0, ti->len,
1136 dm_table_get_mode(ti->table), &dev);
1138 ti->error = "Cannot get target device";
1146 static void origin_dtr(struct dm_target *ti)
1148 struct dm_dev *dev = (struct dm_dev *) ti->private;
1149 dm_put_device(ti, dev);
1152 static int origin_map(struct dm_target *ti, struct bio *bio,
1153 union map_info *map_context)
1155 struct dm_dev *dev = (struct dm_dev *) ti->private;
1156 bio->bi_bdev = dev->bdev;
1158 if (unlikely(bio_barrier(bio)))
1161 /* Only tell snapshots if this is a write */
1162 return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : 1;
1165 #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
1168 * Set the target "split_io" field to the minimum of all the snapshots'
1171 static void origin_resume(struct dm_target *ti)
1173 struct dm_dev *dev = (struct dm_dev *) ti->private;
1174 struct dm_snapshot *snap;
1176 chunk_t chunk_size = 0;
1178 down_read(&_origins_lock);
1179 o = __lookup_origin(dev->bdev);
1181 list_for_each_entry (snap, &o->snapshots, list)
1182 chunk_size = min_not_zero(chunk_size, snap->chunk_size);
1183 up_read(&_origins_lock);
1185 ti->split_io = chunk_size;
1188 static int origin_status(struct dm_target *ti, status_type_t type, char *result,
1189 unsigned int maxlen)
1191 struct dm_dev *dev = (struct dm_dev *) ti->private;
1194 case STATUSTYPE_INFO:
1198 case STATUSTYPE_TABLE:
1199 snprintf(result, maxlen, "%s", dev->name);
1206 static struct target_type origin_target = {
1207 .name = "snapshot-origin",
1208 .version = {1, 5, 0},
1209 .module = THIS_MODULE,
1213 .resume = origin_resume,
1214 .status = origin_status,
1217 static struct target_type snapshot_target = {
1219 .version = {1, 5, 0},
1220 .module = THIS_MODULE,
1221 .ctr = snapshot_ctr,
1222 .dtr = snapshot_dtr,
1223 .map = snapshot_map,
1224 .resume = snapshot_resume,
1225 .status = snapshot_status,
1228 static int __init dm_snapshot_init(void)
1232 r = dm_register_target(&snapshot_target);
1234 DMERR("snapshot target register failed %d", r);
1238 r = dm_register_target(&origin_target);
1240 DMERR("Origin target register failed %d", r);
1244 r = init_origin_hash();
1246 DMERR("init_origin_hash failed.");
1250 exception_cache = kmem_cache_create("dm-snapshot-ex",
1251 sizeof(struct exception),
1252 __alignof__(struct exception),
1254 if (!exception_cache) {
1255 DMERR("Couldn't create exception cache.");
1261 kmem_cache_create("dm-snapshot-in",
1262 sizeof(struct pending_exception),
1263 __alignof__(struct pending_exception),
1265 if (!pending_cache) {
1266 DMERR("Couldn't create pending cache.");
1271 pending_pool = mempool_create_slab_pool(128, pending_cache);
1272 if (!pending_pool) {
1273 DMERR("Couldn't create pending pool.");
1278 ksnapd = create_singlethread_workqueue("ksnapd");
1280 DMERR("Failed to create ksnapd workqueue.");
1288 mempool_destroy(pending_pool);
1290 kmem_cache_destroy(pending_cache);
1292 kmem_cache_destroy(exception_cache);
1296 dm_unregister_target(&origin_target);
1298 dm_unregister_target(&snapshot_target);
1302 static void __exit dm_snapshot_exit(void)
1306 destroy_workqueue(ksnapd);
1308 r = dm_unregister_target(&snapshot_target);
1310 DMERR("snapshot unregister failed %d", r);
1312 r = dm_unregister_target(&origin_target);
1314 DMERR("origin unregister failed %d", r);
1317 mempool_destroy(pending_pool);
1318 kmem_cache_destroy(pending_cache);
1319 kmem_cache_destroy(exception_cache);
1323 module_init(dm_snapshot_init);
1324 module_exit(dm_snapshot_exit);
1326 MODULE_DESCRIPTION(DM_NAME " snapshot target");
1327 MODULE_AUTHOR("Joe Thornber");
1328 MODULE_LICENSE("GPL");